"This reprehensible crime, which we condemn strongly ... should be an additional incentive for everyone to abandon the methods of violence, murder, revenge and terrorism in solving problems," Maliki said.

He said the killings should urge people to accelerate finding a peaceful solution to the 16-month-long Syrian crisis.

The killings on Thursday have sparked an international outcry, and added urgency to deadlocked Security Council negotiations on a Syria resolution.

Iraq, which has a 600-kilometre (375-mile) border with Syria, has voiced support for a peaceful solution to the Syrian crisis which initially began in February 2011.